Pen



FIG. 1 is a front elevation view thereof;

FIG. 2 is a back elevation view thereof;

FIG. 3 is a right side view thereof;

FIG. 4 is a left side view thereof:

FIG. 5 is a top view thereof; and,

FIG. 6 is a bottom view thereof. 

The ornamental design for a pen, as shown. 